Efficiency of exciton dissociation at internal organic interfaces beyond harmonic approximation

• Exciton dissociation at polymer–fullerene interfaces is studied theoretically.
• The effect from interface dipoles is specially focused on.
• Calculations beyond a harmonic approximation are performed.
• Interface dipoles may have a larger impact than anticipated until now.

Understanding the mechanism of the efficient exciton dissociation in multicomponent systems belongs to the most prominent challenges in applied soft-matter physics. The model with discrete dipoles along the internal interface between the different material components is often considered as promising to account for the exciton dissociation. However, the dissociation efficiency in the framework of this model has been so far calculated only within the harmonic approximation. In the current article we calculate the dissociation efficiency in the dipolar model beyond the harmonic approximation and show that the exciton dissociation probability appears drastically larger than assumed so far. We also consider the effect of a finite spatial extent of the dipole charges and show that if the charges cannot be treated as point-like species, harmonic approximation is not applicable.

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